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No brake pedal

Tiny
MIKEDEROUIN88
  • MEMBER
  • 2000 FORD F-150
  • 154,000 MILES
I am working on the truck listed above 5.4 liter engine, four wheel drive with four wheel disk brakes. ABS. And cruise control. The truck had no brakes. There were no leaks in the system and all calipers seem to work fine. I changed the master cylinder and still have the same problem. I bench bled the master cylinder before installation then bled all brakes in the proper order until new fluid came out at all four wheels. Now I can pump a pedal up and it will hold but if I let off for more then thirty seconds it is gone again. I changed the master cylinder again. Bled the brakes again and again and again and still the same. I am totally lost. Any input would be appreciated. Thanks yet again for your help.
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Friday, May 31st, 2013 AT 6:04 PM

10 Replies

Tiny
SINBAD271
  • MECHANIC
  • 169 POSTS
Is the brake light or ABS light on in the cluster? if not you have air stuck in the ABS unit which a scanner will be needs to open the valve when bleeding the system.

This guide can help as well

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Please run down this guide and report back.

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Wednesday, March 10th, 2021 AT 11:02 AM
Tiny
MIKEDEROUIN88
  • MEMBER
  • 137 POSTS
There are no lights on cluster. I am keeping plenty of fluid in master cylinder while bleeding. I bled the brakes both with truck off and while running. I can pump three times and get a pedal. It will even hold pressure if I keep pressing. But if I let go for thirty seconds it is gone again. This is while the truck is running. I have not checked if the pressure is losing while the truck is off.
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Wednesday, March 10th, 2021 AT 11:02 AM
Tiny
SINBAD271
  • MECHANIC
  • 169 POSTS
Try bleeding brakes while truck is off. Leave truck off and see if it loses pedal. If it does not, start vehicle if you lose pedal check to see if your getting engine vacuum at the brake booster by undoing rubber hose at the booster and putting your thumb over the end of the hose it should have suction while vehicle is running. If it does you will need to replace brake booster. You have no power assist for the master cylinder.
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Wednesday, March 10th, 2021 AT 11:02 AM
Tiny
MIKEDEROUIN88
  • MEMBER
  • 137 POSTS
Already checked for suction from booster and it is good. I was told there can be air caught in the ABS module. And since with no brakes I cannot make the ABS come on it is just trapped in there. Is that possible?
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Wednesday, March 10th, 2021 AT 11:02 AM
Tiny
SINBAD271
  • MECHANIC
  • 169 POSTS
The ABS module does not have any fluid. Only the ABS pump. Okay, lets start from step one. You conducted bench bleed right? Did you bleed the lines at the master cylinder. The ones that are directly connected to the cylinder.
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Wednesday, March 10th, 2021 AT 11:02 AM
Tiny
MIKEDEROUIN88
  • MEMBER
  • 137 POSTS
Yes, I did bench bleed the master cylinder. With a bleeder kit as instructed. What do you mean bleeding the lines at the master cylinder? I bled the brakes at each caliper starting at the passenger rear moving closer to the master cylinder until new clean fluid with no bubbles came out.
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Wednesday, March 10th, 2021 AT 11:02 AM
Tiny
SINBAD271
  • MECHANIC
  • 169 POSTS
At the master cylinder there two lines connected correct. Crack open one line a about a quarter turn, then have a helper push the brake pedal down and hold it down. You then close the line, then tell your helper to let up on the pedal, then again open the line again, tell helper to push down pedal and hold it. Then close the line again. Then tell helper to let up on pedal. Do this on both lines until you see a good stream of brake fluid, careful not to let it get all over the place. Do line at the master about three to four times. Then start at passenger rear, have helper pump pedal three times and hold it on the third time than you open right rear line then close it, three times pump pedal hold, open, close. Do this about three to four times each caliper. You should have brake pedal. Caution keep check on master cylinder after each line bleed make sure you do not let brake fluid get to low. Top off brake fluid after each line is bled.
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Wednesday, March 10th, 2021 AT 11:02 AM
Tiny
CHRISTOPHER NULL
  • MEMBER
  • 11 POSTS
Okay, so I am reading this post because I am having the same issue with the same truck. 2000 F150. Four wheel disc. I am guessing four wheel ABS. One on each front wheel, one on rear end. New brake pads and new rotors. Calipers functioning fine. I bought the truck for $200.00. Needed a new fuel pump. Upon test drive I blew a brake line that runs inside left frame rail near back of fuel tank. I was only quarter of a mile from house. Dropped tank and repaired brake line. Today is the tenth time I have bled the system. I did replace master cylinder because of same pedal issues. Bench bled and bled on truck. Have not tried bleeding lines. Gong to try that tonight after it cools down a bit.
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Wednesday, March 10th, 2021 AT 11:02 AM
Tiny
ARNOTTOYH
  • MEMBER
  • 0 POST
I had this problem and had to go to a shop so they could open the ABS valve cost me $150.00 all fixed
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Wednesday, March 10th, 2021 AT 11:02 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,840 POSTS
Excellent addition to this thread! :)
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Wednesday, March 10th, 2021 AT 11:02 AM

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